To solve the lack of program time, which is a problem of a display device including an EL element, and to provide a display device including a pixel circuit with a high aperture ratio and a driving method thereof. In a circuit including a driving transistor, a capacitor, a display element which can be used as a capacitor, a first power supply line and a second power supply line, potentials of the first power supply line and the second power supply line are set to be almost the same, thereby a threshold voltage of the driving transistor is held in the display element, and after that, a charge is divided into the display element and the capacitor.